I've made my icons in Cheetah3d too. Its real easy. Just have a model you want to be your icon. Goto the camera and set the background color to 100% transparent. Make sure the image is 512x512.

In the new developer tools,

/Developer/Applications/Utilities/Icon Composer.app

I think Icon Composer.app is much improved. Just drag and drop to the 512x512 box with image rendered in Cheetah and it will generate all the masks and smaller icons. Then just save to get the icns file. Put the icns in the Resources folder in your app and reference it in the apps plist file. Pretty cool.

Thanks alot for your help! I'll try that. However, right now I'm looking for Button Icons, not App Icons. Also, I downgraded to Tiger so I could follow the flipsquare tutorial(IB changed to much in Leopard for me to be able to follow along).